The French manufacturer Sanofi Pasteur is voluntarily recalling about 800,000 doses of vaccine meant for children between the ages of 6 months and 35 months.

The company and the Centers for Disease Control and Prevention emphasized that the recall was not prompted by safety concerns, and that even though the vaccine isn’t quite as potent as it’s supposed to be, children who received it don’t have to be immunized again against H1N1.

The CDC emphasized that there is no danger for any child who received this type of vaccine.

When asked what parents should do, CDC spokesman Tom Skinner said, “absolutely nothing.” He said if children receive this vaccine, they will be fine.

“I had a cough, sinus infection, infected ear, fever, and that’s when I went into urgent care and tested positive,” Brizendine recalled. “There were times when I honestly could not get out of bed because I was so sick and achy.”

Brizendine began worrying about how the swine flu would affect her baby, due in January.

Brizendine had been preparing for another baby. Her 22-year-old daughter, Kayla Yost, is expecting a girl at the end of this month.

While Brizendine battled the virus, Yost, too, suddenly showed all the signs of H1N1. She was hospitalized and in a battle for her life.

“I was coughing really bad,” Yost recounted. “It was like nonstop. My stomach was in pain because the [cough] was so deep. I was hyperventilating because I could not breathe.”

“The 2009 H1N1 pandemic continues to evolve. The rates of illness continue to rise rapidly within many communities across the nation, and the potential exists for the pandemic to overburden health care resources in some localities,” Obama said in a statement.

“Thus, in recognition of the continuing progression of the pandemic, and in further preparation as a nation, we are taking additional steps to facilitate our response.”

The president signed the declaration late Friday and announced it Saturday.

Calling the emergency declaration “an important tool in our kit going forward,” one administration official called Obama’s action a “proactive measure that’s not in response to any new development.”

The panel also said those first vaccinated should include parents and other caregivers of infants; non-elderly adults who have high-risk medical conditions; and young adults ages 19 to 24.

The Advisory Committee on Immunization Practices voted to set vaccination priorities for those groups Wednesday during a meeting in Atlanta. The panel’s recommendations are usually adopted by federal health officials.

The recommendations are designed to address potential limits in vaccine availability this fall if there is heavy demand and limited supplies.

The government estimates that about 120 million swine flu vaccine doses will be available to the public by late October. Roughly 160 million people are in the priority groups considered most vulnerable to infection or most at risk for severe disease.

Although the number recommended to get doses exceeds the projected supply, health officials don’t think everyone will run out and get vaccinated. Traditionally, less than half of the people recommended to get seasonal flu shots get them. Only about 15 percent of pregnant women get seasonal flu vaccinations.

If there is ample vaccine, vaccinations also would be recommended for all non-elderly adults, the panel also voted. And if there’s still plenty of vaccine, the swine flu shots and spray doses should be offered to people 65 and older. Fewer illnesses have been reported in the elderly, who appear to have higher levels of immunity to the virus, health experts say.

However, the elderly should be pushed to get shots against seasonal flu, which is a significant health risk to older adults.

The move came after an emergency meeting with flu experts here that was convened after a sharp rise in cases in Australia, which reported 1,224 cases on Wednesday, and rising numbers in Britain, Japan and elsewhere.

In a statement sent to member countries, the W.H.O. said it decided to raise the pandemic alert level from phase 5 to 6, indicating a global pandemic outbreak, The Associated Press said, attributing the information to health officials from Scotland, Indonesia and Thailand. An official announcement of the change was due at 6 p.m. Geneva time on Thursday (noon in New York).

In an effort to avoid triggering panic with such an announcement, W.H.O. officials are expected to include a caveat that the flu, which has resulted in mostly mild cases, is not more deadly now that it has been declared a pandemic. Rather, the announcement reflects the global spread of the disease, not an increase in its severity.

According to W.H.O. rules, the organization should declare a pandemic once it finds evidence of widespread “community transmission” — meaning beyond travelers, schools and immediate contacts — on two continents.

It marks an increase of 405 cases and four deaths since Monday evening, said WHO Assistant Director-General Dr. Keiji Fukuda.

Meanwhile, residents in Mexico City restlessly waited for life to return to normal as officials from both Mexico and the United States said the worst may be over in the swine flu outbreak.

Mexican officials, citing improvement in the battle against the Influenza A (H1N1) virus, announced plans to reopen government offices and restaurants on Wednesday — and museums, libraries and churches the following day.

U.S. Homeland Security Secretary Janet Napolitano acknowledged claims by Mexican authorities who believe their cases have peaked. “I have no reason to think that is inaccurate,” Napolitano said.

“What the epidemiologists are seeing now with this particular strain of H1N1 is that the severity of the disease, the severity of the flu — how sick you get — is not stronger than regular seasonal flu.”

But officials from WHO and the CDC plan to monitor developments in the Southern Hemisphere, where flu season arrives over the next few months as winter begins there.